Figure 3

Gp120 interaction with SRCR1 peptides. A) The schematic illustration of SRCR1 sequence. Twenty overlapping 15-mer peptides covering the complete SRCR1 sequence were designed and synthesized. These peptides were numbered according to SRCR1 sequence, P1 standing for 1–15 residues, P2 for 5–20 and so on. The peptides with highest binding index with gp120 were identified and the key binding amino acids were marked with star; B) Recombinant gp120_BaL interaction with peptides derived from SRCR1. Biotinylated peptides (30 μg/ml) was allowed to bind immobilized gp120 (8 μg/ml) and were tested for their binding capability to gp120 with ELISA; C) Nonbiotinylated P19 competitively inhibited biotinylated P19 binding to gp120 (8 μg/ml). Biotinylated P19 (40 μg/ml) was pre-incubated with increasing concentrations of non-biotinylated P19, added to a gp120-coated plate (8ug/ml) and incubated at 37°C for 60 min. Unbound peptides were removed by repeated washing. Since P1 showed no binding to gp120 in previous binding assays, it was used as a control at the maximum concentration (640 μg/ml).